Sprocket milling machine



Jan. 9, 1945. o. cULLMAN ET AL SPROGKET MILLING MACHINE Filed Feb. e, 1945 5 vSheets-Sheet l O. CULLMN ET AL SPROCKET MILLING MACHINE Filed Feb. 6. 1943 s sheet's-sheet 2 i In un O. CULLMAN ET AL sPRocKET MILLING MACHINE Jan. 9, 1945.

Filed Feb. 6, 1945 3 Sheets-Sheet 3 @MMQLW Patented Jan. 9, 1945 UNITED STATES ,PATENT OFFICE sPRiooKE'r MILLING MACHINE OttoCullmamLester H. Hornbrook, and Norman f B. Wienke, Chicago, Ill., assignors -to Cullman Wheel Co.,-Chicago, Ill., a corporation of Illlnois Apeliationrebuary s, 194s',` serial Na. 474,930 l The present invention relates to imiivrovements in milling machines, and it has particular-reference to anautomatc apparatus for milling to proper shape and dimensions the sprocket wheelsi used in cooperation with thelink-belts onthe ootereillortroads of .military ,tanks .trootorsf and nienke'. I

provide a highly efficient apparatus which, will rapidly, automatically, and dependablyj per-form its required functions.` Another'wobject of this invention is to simplify the construction of` an apparat-11S of vthe Character oontomplotod heroin, and to improvev the. operation of Such, apparatus .Still another object is `to.turca/ idoo'machine which'hwilliaccurately mill Ythe working edgesvof arpluralityof sprockets during a1 single cycle oi operation. l

A Yfurtherobject is to provide a machine Wherein at leastvtwo sprocket `blanks inl reversed posi-y tions are operated upon simultaneously, with the vmilling tools working `upon corresponding edges of the teeth of the two blanks. -I l i Y, Further objectsY are to providea millingmachine whereinthe millingv toolwill Voperate upon therkleading edge of a,y sprocket tooth, and after c ompleting the work on said edgewill be automatically shifted totheleading edge of the suc:

Gooding sprocket tooth,.iand,this operation; Conf:

tinued untilthel leading edges of the` entireseries ofv teeth of a sprocket have b eeonshed: to prof` vide that at the end of,e,ach milling operation upon a tooth themilling toolvvill bebodily moved and rapidlypassfrem `thetip Yor crestjofthe addendum of said tootliwto aninner portion ofr the adjacent root groovewithout contactingthe trailingedge of the tooth from whichv said tool 8v Claims.

, It isjthe principalfobjct of, thislinventionto portiebf' a sprocket tooth upon which it has been'operating.

Fig. 5 is another diagrammatic view showing further rotatve'movement of'the template and corresponding sprocket tooth and also showing the pathof bodily movement of the milling tool into position to `start operation upon the leading edge of the,neX'ttoot-h.`v f

Fig. 6 is merilar'ged` detail, partly in longitudinal section,`i the milling tool, its guide roller,v

' and the mounting of the arbor therefor.`

In the form shown, the instrumentalities Ifor holding the work aremounted upon a support or pedestal I0 which arisesfrom the central portion of a base I I which also provides the bottom of a tank orAV reservoir dened by upright walls I2. At

has been disengaged; to provide `improved escapement means-controlled by theV template for transition of the tool from one tooth to the next -without engagement withthe Vtrailing edge of the tooth and for retarding'of the bodily move,-v

ment ofthe tool; andv to Aprovide improved means blank-S. ,n Y: "fl,

A preferred embodiment of this inventionis hereinafter described and. shown in the panying drawings in'which:

for readily mounting and dismounting the work Figure 1 is a longitudinal sideelevationof apparatus such as" contemplated hereinorauto-r matically7 milling the teeth oi?sproclretsY s f -1ig.2isa vertical transverse lsectional viewbf the same,takenonline 2.-2-Vof` Figure ,1., ,I l

I'Fig. 3 is a fragmental verticalsectiontaken axially through theV templatea'nd blanklsupporting.r arbor, the View being'taken along -the plane of line 3--3 on Figure .1, looking in thedirection o'f the arrows anddrawn to-a larger scaleg` Fig. 4 is a diagrammatic-view'showingtravelof thefmilling tool being. moved Vfrtnntip thetop of the pedes'tal'there is ahorizontal shelf I3 which provides a supportfo-r a lheavy bearing block I4 that is bfoltedto'said shelf and provided Witha horizontalborefor Vjournalli'ng the main arbor I5. Both Yendsf the. arbor project beyond the bearing block as willbeV seen nFigures'Z and. 3 and these extended ends of the arbor have v the""Work-'carrying members keyed to them sothat said members willirotate'simultaneously in the same direction. Each of these workcarrying members consists of' a bodyv lllH axially bored 'to iitan end'ofithearborlj. o

`One of these members l6',"a`s shown in Figures 2 and 3,' is provided with an annular'seatA I1 in which a. comparatively.V large sprocket YI 8- is secured` byneans ofi' bolts I9."r The sprocketll drives the work-'carrying members andthe arbor I5, kand -itis connected byV a link belt 20A with asprocketlZI keyed tothe adjacent end portion' ofla 'rotatable drive shaft22. Suitable meansv are employed fondriving the Shaft 22 to' turn the arbor I5 and AWork-carrying members -'I6 -at thefproper speed so'that each Ytootlijof a blank will vremain in coactive vrelation` to the millingv too-1 the propel' length oftime' fork the tool to f tical section of the workjsupportingwheel member at the left 4@nu Vof dme arterie in Figure 2,

andsinceboth Wheel membersareiof the same construction (with thefexception Yofthe sprocket I8) this detaileddescription thereof will beiconfined.' to Figure 3 andthe ,same reference characters willjdentifysimilarfparts-,on tht-:other n,

wheel member. The annular outer edge of the wheel body I6 is provided with a. circumferential rib 2l which is adapted to provide a mountng for the template or pattern 28 which is of ringshape and may be one of the finished pieces of work. A rabbet 29 around the edge of its central opening permits the template to be seated upon the corner portion of the rib 2l nearest the ring gear i8 and to be secured to said rib by means of bolts. 30 which pass through the template and are screwed into threaded openings in the adjacent side of said rib. The circumferential contour of the template 28 conforms with the nished shape of the work piece, and in the form shown, is provided with a plurality of `radially projecting teeth 3l having edges 32 formed in compound curves as suggested in Figures 1, 4 and 5 wherein it will -be seen that the teeth have generally triangular shapes disposed with the tips 33 outermost and with root grooves or recesses 34 between these teeth. The template rotates clockwise in Figure l, as indicated by the arrows, and the crests 33 of its teeth 3l are provided with projecting lugs or lips 35 which function in the manner o' an escapement for the milling tools to clear the trailing edge oi each tooth. This will be more fully explained in a subsequent portion of this description.

The work piece upon which the milling tool operates may be a ring-shaped disc 36 similar in its general outline to the pattern or template 28. The work item shown by way of example in the drawings has a rabbet 38 formed around the edge of its central opening. This permits its being seated upon the corner portion of the rib 2l on the opposite side thereof from the template Where it is securely mounted by special clamping instrumentalities to permit the ready removal of the work piece 36 at the end of each cycle of operation of the apparatus.

The devices for attaching the work piece to the wheel rib 21 preferably consist of an annular clamp disc 39 which has a central opening oi such diameter that it may be slipped upon the extending hub 40 of the wheel member |6, and the overall diameter of said clamp disc 38 is sufcient to have an outer marginal portion to overlap the inner marginal portion of the work piece 3S in the manner shown in detail in Figure 3. Bolts 4I pass through apertures421in the clamp-disc and screw into threaded holes in the adjacent side face of the wheel member I6, and it will be noted that the diameters of the apertures 42 are greater than the widest portions of the heads of bolts 4| so that the clampdisc 39 may be readily taken 01T the hub Y40 of the wheel member without removing the bolts from the threaded holes in the side of said wheel member.

Heavy U-shaped washers 43 are interposed between the heads of the bolts 4| and the adjacent outer face of the clamp-disc 39, said washers being of a diameter which is larger than the apertures 42 so that said washers will engage the face of the clamp-disc around the apertures 42 when the heads of the bolts are tightened against the outer faces of said washers. Thus it will be seen that when it is desired to remove the` work piece, the bolts may merely be loosened, and after the U-shaped washers 43 have been displaced from the Shanks of the bolts, the clamp-disc may then be removed and the work piece 38 also unseatedv from the wheel member I6. The reverse of this operation takes place when another work piece is substituted for the pieceA which has been removed.

The milling tools, together with the guide rollers which cooperate with the templates 28, are suitably mounted upon a rotatable spindle 44 which-is journaled in spaced bearings 45 which are mounted for bodily movement in a path that intersects the path of the teeth on the work in the p-lane of its rotation as the guide rollers are following the contours of the templates 28, The bearings 45 are a portion of a rocking frame comprising a U-shaped bridge piece 4G and spaced supporting arms 41 which are also connected at their lower ends by means of a hollow connector 48. A rock-shaft 49 which passes through connector 48 is mounted in spaced bearings 50 which have flanges 5| secured to the base ll by means of bolts which securely anchor the rocking frame-structure in a manner to prescribe the bodilyy movement of the upper portion of said frame with respect to the work pieces and templates during the operation of the apparatus.

The rotatable spindle 44 is reduced in diameter within the bearing bosses 45 to provide shoulders 52 against which oil and dust seal devices 53' are abutted bymeans of closure plates 54, and back of said spindle shoulders there are anti-friction devices 55 that are interposed between the bosses and the adjacent portions of the spindle and are maintained in position by `closure plates 55. This arrangement is illustrated in detail in Figure 6. The end portions of the spindle 44 project beyond the bearing bosses 45 and are reduced in diameter to provide` shoulders 51 near said bosses, which shoulders 51 act as abutments for the guide rollers 58 which are rotatable on the spindle independently of the rotation of the latter. Beyond the rollers 58 the spindle has the milling tools or cutters 59 secured to it by keys 6U (Figure 4) so that said tools will be rotated at the same speed as the spindle 44. It Will be seen, by reference to Figures 2 and 6, that the guide rollers 58 and cutters 59 are disposed upon the rotating spindle 44 in spaced relation to each other and they are` in planar alinement respectively with the templates 28 and the work-pieces 36. The spindle 44, since it is rotatably mounted on the rocking frame of which the arms 4'! are a part, is adapted through the medium of the guide rollers 58 to follow the contour of the templates and in so doing will cause 'the cutters or milling tools I55 to engage and shape the edges of the work pieces in an exact duplication of the workshaping contours of the templates 28.

The spindle 44 has its extremities rotatably journaled in bearings 6l at the adjacent ends of removable bracev aims 62 having split collars 63 that are firmly clamped to the adjacent ends of a horizontal bar 64 of the rocking frame. Beyond the bearings 6I the ends of the spindle 44 are reduced and threaded to receive nuts B5 to bear against the ends of the bushings 66 which prevent axial movement ofthe spindle. The milling tools 59 and their adjacent guide rollers 58 are separated from each other` on the spindle 44 byl pairs of ring spacers (il,l and suitable baflle discs 68 lare mounted between the ring spacers in order to prevent chips from the work from striking the guide rollers 58 and their respective templates and possibly causing inaccurate cuts.

The Spindle 44 is rotated, at high speedbymeans. of'wheel 69', a link belt 10, wheel 1I and: a driving member 19. The horizontal bar B4 and the crossmember19 are disposed, the former above the latter, as shown in Figures 1" and 2, and they are welded or otherwise permanently secured to ad'- jacent portions Iof the rockerarms i1 and thereby assist in strengthening the swinging frame which carries the operating spindle. v e

f In order to rmly maintain the platform in de' sired'relation to the other parts of the swinging frame suitable oblique struts 80 are provided which have their Alowerends secured tothe fulcrurn or rock-shaft y49 vand have ytheir uppenend f portions provided with elongated slots -8|' toreceive lateralv studsv 82 by which the platform may be lockedvin desired relation to the" swinging frame. By releasing the clamp bosses 18 and theA securing devices for the studs,1theplatform may be swung upon the bar '19 as a fulcrum inl order" tftighten kor loosen the belt 1U" between the Although the work-,carrying arbor I isp-rotated 'at fa relatively slow speed,l the )tool-carrying .spindle 44'is rotated at a very high speed, and said spindle, together with its movablesupport oroar-y f v rier, isconstantlyurged in the direction of the work by suitable novel instrumentalities whichv are clearly shown in Figure 1.- f

An elongated bell-crank element or that i's'secured to and' projects from aportionxof the .pedestal I0 above the plane of the top yof the formedon thework piece lor blank 36. reaching the crest ofa temp-late tooth, the guide` f therein to keep `the dash-pot properly supplied. It' will be understood that when the `piston 94 vbegins to move downward from an upper posi- `tion above'the uppermost -port or opening 95,(the

liquid in the dash-pot will be forced through all v of said openings and the movement ofthe piston will be faster than after so-me of the openings have been closed by said piston, yand as a consequence, the lower the piston travels down in the dashpot the slower will be the downward movement of the weighted bell-crank arm 83; thus retarding the downward motion of'thebell-crank arm and avoiding shock as the cutter engages the work. j

The pull of the weight 9| forces the rocking frame vin the direction of the main work arbo-r causing the guide roller 58 and the milling tools V 59 to bear firmly against the respective templates 28 and work pieces 36, and while this main arbor is slowly rotating in a clockwise direction (Figure l) the rollers will follow the contour of the leading edges of the teeth on the templates 28 andthe milling tools'will correspondingly 'cut and shape the leading edge of the tooth being Upon roller will continue in contact with thetrailing lug on the template tooth andwill hold the milling vtool 59 in a position where it is vout of engagement withthe work piece and this disenam 83 is fulerunied on a pin 8,4 'carried by a, bracket 85 gagement will kcontinue until the'guide roller leaves kthe yend of said lug 35. In the meantime, the main .arbor has continued to rotate the template rand workpiece tooth, which has just been out, in an upward arc to a positionso that when the roller leaves the control lug 35 the rocking frame which carries the spindle will rapidly swing upon its fulcrum 48, due to the action of the weight 9|, until the roller and the cutters have reached the root groove or recess 34 between the tank l2,` and the upper arm of this "bellecrank v leverf`83 ispivotally connected vtoforle end ofl a horizontal link 86rthat extends pastytheipede'stal land vhas its other end pivotally connected to a bracket"k 81 on the 'rockingr frame between the rocker' arms 41. The' long arm of the bell-crank lever B4 extends4 beyond the end-ofthe tank, l2

lwhere it is provided with a. pendant ,weight-link 88 which has ay supporting discfl` at'itslwer end and has its bifurcated upper end 90 pivoted tofth'e f end' ofthe beu-Crank erm s4. The weigntsel which are carried by the link 88 are: of preponf derating size in order to considerably over-'bal-l ance the tendency of the rocker-frame, the motor 13 ,andy the platform 16 to pull the tool-carrying spirl'dle'away from the work,'and this over-balancing weight is also suiiicient to urge the milling teoisjaridthe guide rouers nrmiy against theirl respective work pieces and templates. 1

The bell-,crank lever 83 isl provided intermediate the weightedend and the fulcrum bracket 85 with a depending pitman rod v9,2 thatextends into a dash'pot 93where its lower end is pivotally connected to aipiston 94having reciproeablesliding movement in said vrdash-pot.v At the lower v each tooth to the next succeeding tooth in an# portion ofthe wall ofthe 'dash-poty93 there is a seriesof openings `95 past which the inner end ofthe piston is adapted to move andsuccessively close said openings to act as a. brake and gradually slowdown or retard themovement of the bell-crankarm'83v in a downward direction. Thev dash-pot,isApreferablyzdisposedl within a receptaclel or chamber 96 at the end of the tank I2 and a. suieienty level of liquid is maintained teeth, and during this movement the rollers and kcutters will be inactive upon the template and 'the work piece. The start of this swinging movement of the rocking frame and the operating spindle 44 will be rapid, but as. the rollers and cutters approach the root groove 34, the swinging movement'will have been slowed down' because of the fact that the piston 94, which controls the movement of` the bell-crank arm 83, will have v.reached a lower position in the dash-pot whereit has'begun to close the openings 95 which reduces the discharge of the liquid therethrough. The

kguide rollers and cutters then are in position to begin loperation upon the leading edge of the'r next tooth. f

yThis mode vof operationy will continue fromautomatic manner until the leading edge of the last tooth ofl the sprocket has been cut.y The `work pieces are then removed and, remounted in reversed position ulpon the opposite end of the arbor I5, so that the previoustrailing'edges of the teeth vof the sprocket then become the leading edges; and the cycle of operation is started with the cutting taking place upon the then leading edges of` the teeth, and continues until the final tooth hasbeen formed.

vIt is to be observed that, the axes of thercutter spindle and the ywork arbor are parallel and that the path of the bodilymovement of the ycutters isflinear land intersects the radius of the 'Y tooth that is being 'surfaced at an acute angle so that the cutters properly. follow'the template due to the rotation of the lattenV When the tem'-v plate and work have made one complete revolution, the work is remounted in reversed position on. the. opposite end of the arbor andi is ccm pletely finished at the end of the next complete, revolution of the arbor,

Although but one speciiic embodiment oi the invention is herein shown and described,V it will be understood that numerous details may be altered or omitted without departing from the spirit of the. invention as dened by the following Claims.

We, claim:

1. A milling machine, comprising an arbor,y a template on said arbor having sprocket teeth, means for xing a toothed sprocket blank in tooth-registering rotative relation to said template, driving means for rotating said tempi-ate, a spindle journalled on an axis parallel with said arbor and having a guide wheel and4 rotary cut,- ter thereon respectively alined with saidv template and blank, a carrier for moving said spindie in a path disposed across the path of the teeth on said template in the plane of rotation thereof, driving means for rotating said spindle, and means yieldingly Aurging said spindle toward said template, said template having extensions on the trailing sides of'its teeth to cause said cutter to pass clear of the trailing sides of the teeth on such blank.

2. A milling machine, comprising a frame, an arbor mounted on said frame, a template on, said arbor having sprocket teeth, means for fixing a toothed sprocket blank in tooth-registering rotative relation to said template, driving means for rotating said template, a spindle J'ournalled on an axis parallel -with said arbor and having a guide Wheel and rotary cutter thereon, respectively` alined with said template and blank, a carrier pivotally mounted on said framer on ariv axis parallel with said arbor, for moving said spindle in a path disposed across the path of the teeth on said template in the plane of rotation thereof, driving means for rotating said spindie, and a lever fulcrumed on said frame, be`- ing linked to said carriage and counterweighted to normally urge said spindle toward said template.

3. A milling machine, comprising a frame, an arbor mounted on said frame, a template on said arbor having sprocket teeth, means for fixing a toothed sprocket blank in tooth-registering rotative relation to said teirnolate,l driving means for rotating said template, a spindle journalled on an axis parallel with said arbor and having a guide wheel and rotary cutter thereon respectively alined with said template and blank, a carrier .pivotally mounted on said frame on an axis parallel with said arbor for moving said spindle in a path disposed across the path of the teeth on said template in the plane of rotation thereof, driving means i'or rotating said spindle, a lever fulcrumed on said frame, being linked to said carriage and counterweighted tov normally urge said spindle toward said template, and a dashpot acting between said lever and frame to control the movement of said carriage and prevent shock to said cutter as it passes from one tooth to the next on said blank.

4. A milling machine for cutting sprocket teeth, comprising a rotatable template, means for holding a Work piece fixed Iwith respect to said template, a tool adapted to operate upon said work piece, means for bodily moving said tool with respect to said template, a portion of said bodily movement `being an accelerated motion of; the toolv towards the root of the; sprocket teeth` ing said tool under control of said guide meansr and template, means for causing ther tool to leave said work piece and move with accelerated bodily motion towards a root groove to position` said tool to operate upon a portion of another tooth, and means for retardi-ng such accelerated bodily motion of said tool at a predetermined position.

6,. A milling machine, comprising a support,y a template rotatable on said support, a work piece secured for rotation with said template, -a rock frame fulcrumed below said template for swinging movement towards and away from said support, a rotatable guide member on said rock trame positioned to engage said template, arotatable milling tool` on said rock frame positioned to engage said Work piece driving means mounted on said rock frame for actuating said milling tool, a, bell-crank operatively connected to said rock frame,` and a weight on said bell-crank adapted to. urge said rock frame in a direction toy normally maintain said guide member and said milling tool engaged with said template and said work piece.

7. A milling machine comprising a support, ran arbor rotatably mounted thereon, a template carried by said arbor, a Work piece carried by said arbor, a. rock frame adapted for swinging movement towards and away from said support, a.` rotatable guide member on said spindle positioned to engage said template, a rotatable milling tool 0n said rock frame positioned to engage said Work piece, driving means on said rock frame for actuating said milling tool, ,a bell-crank. operatively connected to said rock frame, a weight o n said bell-crank to urge, said rock frame in a direction to normally maintain said guide member and said milling tool engaged with said template and said work piece, and dierentially acting braking means, controlling the` movement of said bell-crank.

8. In a milling machine, a. rotatable arbor, av disc-shaped template xed on said arbor,A said template provided with a plurality of radially disposed projectionsupon its margin, the sides of said projections providing leading and trailing edges during rotation of said arbor, trailing lugs at the outer portions of said projections, means for mounting a work piece in xed relation to said template for rotation therewith, a rotatabley cutter in position to engage the leading edges of said' work piece, means normally urging said cutter towards said Work piece, and a guide for said cutter normally in active relation to the leading edges of said template projections, sai-d guide adapted upon engagement with said lugs to cause said cutter to escape the successive trailing edges of said work piece projections.

O'I'IO CULLMAN. LESTER H. HORNBROOK. NORMAN B. WIENKE. 

